Apparatus for measuring and detecting x rays



Oct. 20, 1925- T. W. CASE APPARATUS FOR MEASURING AND DETECTING X-RAYS' Filed March 51. 1921 at)! ws/vro I M Patented Oct. 20, 1925.

UNITED I STATES PATENT OFFICE.

THEODORE WILLARD CASE, OF SCIPIO, NEW YORK, ASSIGNOR TO CASE RESEARCH LABORATORY INCORPORATED, OF AUBURN, NEW YORK, A CORPORATION OF NEW YORK.

APPARATUS FOR MEASURING AND DETECTING X RAYS.

. Application filed March 31, 1921. Serial No. 457,284.

To all who it may concern:

Be it k fi own that I, THEODORE W. CASE, of Scipio, in the county of Cayuga, in the State of New York, have invented new and useful Improvements in Apparatus for Measuring and Detecting X Rays, of which the following, taken in connection with the accompanying drawings, is a full, clear, and exact description.

This invention relates to a new apparatus for detecting and measuring X-rays from radium.

The broad object of the invention is to produce an efficient apparatus of sensitive character capable of detecting the presence of and indicating a relative value for X-rays.

Other objects and advantages-relate to the details of construction and arrangement of parts of the apparatus, as, will more fully appear from the following description, taken in connection with the accompanying drawings, in which:

The figure is a diagrammatic illustration of an apparatus of my invention.

The apparatus, as shown, comprises an evacuated bulb -1-- enclosing a filament 2-, a grid -3 and a plate -4. The

id in this instance, is formed of nickel, as that metal is found adapted for my purpose. However, various other metals or substances may be found suitable for accomplishing the object of this invention, and

do not, therefore limit myself to this particular metal or substance of which the grid shall be formed.

The filament -2-- may be heated in any suitable manner as by connecting the same in circuit with a battery --5- and a variable resistance 6 The filament is also connected with the plate -4. by a circuit containing. a source of potential 7- and a measuring or indicating device, as the galvanometer 8-.

Preferably the voltage of the battery 7 should be adjustable'so that the potential across the filament and plate may be variedrand forthisfpurpose-l have pro-- vided a mult1-pomt switch -9 tapped in at various points of the battery.

The connection between the filament and plate should be made in such a manner that a positive potential is maintained upon the plate, and a negative potential maintained upon the heated filament.

The filament is also connected with the grid -3 by a circuit containing a source of potential,- as battery 10-. Preferably the voltage of the battery -1() should be adjustable so that the potential across the filament 2- and the grid 3,- may be varied, andfor this purpose I have provided a multi-point switch 11-+ tapped in at various points of the battery -10-. The connection between the filament and grid should be made in such a manner that a positive potential is maintained upon the heated filament and a negative potential is maintained upon the grid.

If this latter circuit between the filament and the grid were omitted, and a suitable potential embodied in the circuit connecting the filament and plate, when the filament is properly heated a current will flow between the filament and plate, the direction being from the positive plate to the negative filament. When the circuit described between the filament and grid is included, and a negative potential maintained upon the grid, the current flowing between the plate and filament is decreased to an extent proportional to the value of the negative potential of the grid. It is found that a suificient negative potentlal can be maintained upon the grid to stop all flow of'current between the positive plate and the filament.

For the purpose, however, of detecting and measuring X-rays, it is preferable that the potential of the battery 10 should be so related to the potential of the battery 7 that a proportionately small current flows in the circuit between the plate and the filament.- As illustrative :-a potential of sufiicient value can be maintained upon the grid so that about one-fifth of the normal current flows between the plate and filament. With the sources of potential so adjusted, the apparatus is in condition for operation in a manner that is at .present perhaps preferred, although different relative adjustments may be made without departing from this invention.

Any suitable source of X-rays may beutilized as part of my apparatus, and m Figure 1 I have diagrammatically illustrated a known form of suchapparatus comprising a tube 11 -containmg a filament -12 adapted to be heated in any suitable manner as by a heating circuit including a battery -13'-, the filament being connected in circuit with an anode 14, such circuit including a source of potential, as battery 15-. The ano e 14 as illustrated, is in the form of a p te The X-ray tube operates in the usual manner by bombardment of the anode 16+ by the cathode rays given oil by the heated filament -12--, the X-rays emanating from the plate or anode -14- as a result of such bombard ment.

It is found that when the tube 1 containing the reactive grid -3 and the filament 2- and plate connected as described, is exposed to X-rays, that the fi] rays cause the expulsion, or emission of jeo.

negative electrons from the nickel grid, leaving the grid more positive, thereby effecting a large increase of the current flowing in the circuit between the plate and filament, this variation being indicated and recorded inknown units of value by a suitable measuring instrument, as the galvonometer 8-, as for illustration, an increase in intensity of the ra s will increase the current flowing 1n the plate filament circuit.

As above stated, nickel is found to be a substance suitable for forming the grid 3-, but .it will be understood that any other substance sensitive to X-rays under the conditions named may be substituted for that here described.

Although I have shown and described a specific construction, arrangement of the the appended claims.

parts of the apparatus, and particular connections for thesame, I do not desire to limit myself to the details of form, construction, or arrangement, as various changes may be made in each, without departing from the invention as set forth in What I claim is: a

1. An apparatus for determining X-rays comprising the combination'witha source .of X-ra s of an evacuated bulb, a pair of spaced e ectrodes arranged within the bulb, means for heating one of the electrodes, "a circuit connecting the electrodes and including a source of potential, andfa third electrode within thebulb adapted to giveofi electrons under the influence of .X-rays to thereby vary the current flowing between the first two named electrodes in'accordance with the intensity of the X-raysv to which the third electrode is exposed.

2. An apparatus of the class described,

comprising the combination with a source of X-rays an evacuated bulb, a filament and a plate arranged within the. bulb, means for heating the filament, a circuit connecting vice in accordance with the intensity of the X-rays to which said member is exposed.

3. An apparatus for determining X-rays comprising the combination with a source of X-rays an electro-ionic discharge device, means for producing an artificial resistance to the flow of current from the plate to the filament of said device, and means res onsave to X-rays for varylng such artificla reslstance.

4. An apparatus for determining X-rays comprising the combination with a source of X-rays a vacuum bulb, a filament and a plate within the bulb, means for heating the ament, a circuit connecting the filament and plate and containing a source of potential with its positive pole connected to the plate and its negative'pole connected to the filament, a third electrode, a circuit I connectin" the filament and the third electrode, and containing a source of potential with its positive pole connected to the filament and its negative pole connected to the third electrode.

5; An apparatus for determining X-rays comprising the combination with a source of X-rays an evacuated bulb, a filament and a plate within the bulb, means for heating the filament, a circuit connecting the filament and plate andcontaining a 'source' of potential, with its positive pole connected to the plate and its negative pole connected I to the filament, a third electrode sensitive to X-rays, a circuit connecting the filament and the third electrode, and containing a source of potential with its positive pole connected to the filament and its-negative pole connected to the third electrode.

6. An apparatus for determining X-rays comprising the combination with a source of X-rays an evacuated bulb, a filament and a plate within the bulb, means for heating.

the filament, a circuit connecting the filament and plate andcontaining a source'of potential vwith its positive pole connected to the plate and its negative pole connected to the filament, a third electrode, said third electrode giving off electrons under the influence of X-rays, a circuit connecting the filament and the third electrode, and conv taining a source of potential with its positive pole connected to the filament and its negative pole connected to the third elecmas.-

.7.'An apparatus foidetermining X-rays comprising the combination with a source .of X-rays an electro-ionlc discharge device,

and a third electrode sensitive to X-rays interposed between the filamentand plate of such device, and means for maintaining a negative potential upon said third electrode of a alue suflicient to materially decrease the current flowing through the electro-ionlc discharge device.

8. The method of transforming X-rays by.

through the electroionic discharge device and varying such resistance in accordance with the intensity of X-rays.

In witness whereof I have hereunto set my hand this 28th day of March 1921.

THEODORE WILLARD CASE. 

